X-ray diffraction studies of the structure of liquid and supercritical water at high temperatures and pressures. II. The molecular density radial distribution functions and the paired correlation functions

Conclusion

The present part of this study has given the RDF of liquid and supercritical water, obtained using a procedure which decreases considerably the influence of the main error of the Fourier transformation, associated with the insufficient range of the original structural function. Nevertheless, it is not possible to eliminate completely the idea that the characteristic features observed are due to errors in the treatment and the uncertainty in the experimental data. On the other hand, the refinement of the parameters of the function Y(s) with the assumption that they have a more or less smooth temperature dependence should lead to a considerable decrease in the influence of random errors.

In the discussion of the radial distribution functions, we have tried to present only the experimental facts, without trying to establish a correlation between the RDF and any existing model of the structure of water. This approach to the presentation of the experimental material was determined not so much by caution as by the fact that the correlation functions describe the correlation of fluctuations [13], and from this viewpoint, any of the proposed structural models appears too static to provide a quantitative description, particularly at high temperatures, of the spectrum of possible states making a contribution to the experimental correlation functions.